In long stroke grippers, a so called rod lock device utilizes friction to hold a gripper's jaws in place in case power is lost to the gripper to avoid dropping the part. The device is air piloted to remain open during motion of the gripper jaws but will lock by an internal spring when air pressure is removed. This enables a gripper to be plumbed in such a way as to maintain jaw position in case of pressure loss. These devices mount outside of and onto the body of the gripper. They lock onto a separate shaft that is attached to the gripper jaws, like sidecars.
Several disadvantages of this type of system exist. The shaft and lock are usually side mounted and take up a significant amount of space around the gripper. The rod lock is expensive and requires additional bracketing, housing and shafts to accomplish locking. The lock shaft and lock mechanism are subjected to contamination that can reduce the holding force or cause the lock to fail. The shaft and lock mechanism design uses more parts and thus inherently adds more weight. This reduces the pay load on the gripper, making the gripper less favorable for application in the robotic and aerospace industries. The rod lock may be utilized on one or both grippers.
The present design overcomes the deficiencies of the prior art. The present disclosures provides a locking device that is integrally mounted into the jaws to enable locking of jaw motion if fluid pressure is lost. Additionally, the locking device may provide additional holding force. The present disclosure provides a locking device that is compact and is protected from contamination by being positioned inside the jaw and locking onto the provided guide shafts. The locking device is positioned within the sealed jaws rather than externally to the jaw and thus it is not exposed to contaminants. The lock may be applied into one or both of the jaws. Additionally, the lock may be utilized to provide additional locking force for high pressure grip applications.